This invention relates to methods and apparatus for sealing pavement joints or seams in general, and in particular to methods and apparatus for sealing pavement seams which do not require the utilization of liquid sealing materials which must be heated to predetermined temperatures to achieve molten states.
It is well known in the prior art that when large expanses of concrete are poured and allowed to harden over a relatively dynamic base, such as soil, subsequent movement of that base will result in fractures and cracks in the concrete. These fractures and cracks are due to temperature and moisture gradients which exist in the concrete due to differences between the temperature and moisture content of the top and the bottom of a pavement slab. In an effort to direct such fractures and cracks along less damaging lines, it has become common practice to produce seams in such concrete expanses by cutting or sawing the concrete after hardening, or by utilizing some flexible material which is imbedded in the concrete while it is still in a plastic state. The utilization of cut or sawed seams is most prevalent in this area, particularly in applications such as parking lots and streets or highways.
It has also become known in the art that some form of flexible sealant must be inserted into such seams to stem the increased flow of surface water into the base beneath these seams. The sealant utilized must be capable of withstanding repeated expansion and contraction as the pavement expands and contracts with temperature and moisture changes. This is particularly important in areas where the soil contains a high clay content as the surface water which flows through such seams will result in a significant expansion of the subsurface soils and have a particularly deleterious effect on the stability of the concrete. Thus, it has become necessary to seal these concrete seams with a waterproof material to prevent damage to the concrete structure. Further, the sealant material must preferably be contained entirely within the seam or gap to prevent its removal if it adheres to the tires of vehicles passing over the seam.
The prior art solution to this problem has consisted almost entirely of expensive and difficult to install modern plastic materials or heated asphaltic materials which are difficult and dangerous to utilize. Numerous examples of devices which utilize asphaltic materials and an accompanying heating device abound in the art. The difficulty in utilizing a heated mass of asphalt and accurately applying such materials into a narrow gap has generally been well recognized; however, no acceptable alternative has been proposed. Thus, while this technique is quite dangerous, it has remained the primary method of sealing pavement seams.